Miter joint for hollow plastic frame members

Abstract

An angular connection for a frame or counterframe composed of hollow sections of plastic material includes at least one plastic angular element inserted with its two legs fitting firmly in the hollow sections at the point at which they converge. The walls of the sections are welded to the legs of the insert by ultrasonic spot welds. A second plastic insert may be provided for connecting together edges of the sections, the first plastic insert being arranged to connect the main bodies of the sections together. Both inserts are connected to the hollow sections by ultrasonic spot welds. A method of making an angular connection for a frame and counterframe includes the step of welding hollow sections to at least one plastic angular element using ultrasonic welding techniques.

We claim: 
     
       1. An angular connection for a frame or counterframe composed of converging hollow sections of plastic material, the connection comprising at least one plastic angular element having legs, said legs being inserted and fitting firmly in respective ones of said converging sections. walls of said sections being welded to said legs by ultrasonic spot welds, wherein said plastic angular element connecting said bodies of said sections is in the shape of a hollow "L" having internal partitions connecting short walls with the long walls of said "L", and including at least one ultrasonic spot weld applied to the outside perimetric surface of said bodies of said sections in correspondence with said partitions. 
     
     
       2. An angular connection according to claim 1, wherein each of said sections has a hollow main body and a hollow edge acting as a shoulder, and wherein said at least one element comprises a first plastic angular and a second plastic angular element respectively connecting said bodies and said edges of said sections. 
     
     
       3. An angular connection according to claim 2, including at least one ultrasonic spot weld on the outside perimetric surfaces of said bodies of said sections in correspondence with each of said two legs of that one of said plastic angular elements connecting said two bodies of said sections. 
     
     
       4. An angular connection according to claim 3, including at least one ultrasonic spot weld on said shoulders of said edges of said sections in correspondence with each of said two legs of that one of said two plastic angular elements connecting said edges of said sections. 
     
     
       5. An angular connection according to claim 2, including at least one ultrasonic spot weld on said shoulders of said edges of said sections in correspondence with each of said two legs of that one of said two plastic angular elements connecting said edges of said sections. 
     
     
       6. An angular connection according to claim 2, wherein, said second plastic angular element connecting said edges of said sections is in the shape of a solid "L".